I would like to continue the theme begun last week with another important topic: worm castings. There are great articles on how to produce it in the home, in the business/institution or as a commercial product, so I shall not reproduce what others have articulated so well. Rather, I shall briefly chronicle how Wellfield uses castings in its operations.
There are of course many great benefits to worm castings with few drawbacks. Like other compost amendments one can add, castings (worm manure) increase soil porosity, aeration, drainage and water/nutrient holding capacity. Like other well produced compost soil amendments, use of worm castings adds soil microbes, a critical part of a healthy, living soil. But like other forms of compost, I would not look to castings as a fertilizer. Worm castings contain small levels of NPK and trace elements needed for healthy plant growth, but it is insufficient to really contribute much directly. That is not why I spread compost or castings.
One of the challenges of compost, castings or compost teas is consistency. Casting consistency (say that three times fast) depends on the worm species used and what they feed upon. This can change from batch to batch. As a soil amendment and soil inoculant, I am less concerned about consistency as long as I am not spreading compost with phototoxic material aboard (think stinky compost). It is important with soil amendments and fertilizers to know the ingredients and process used (so develop a local relationship with someone you trust).
Wellfield Botanic Gardens incorporates worm castings into its display potting media. The results, anecdotally, have been very positive. This year we will be top dressing shrubs and tropical plants in our nursery with castings as well, so our current stock does not sit too long on the shelf. We partner with local company RAW Sustainable Living and sell their worm castings in our Visitors Cottage as well.
Further, worms represent, in a large way, an important permaculture principle of producing no waste. It is a great challenge to see the waste we produce as a potential resource to solve another problem. Worms example this principle. I can take my food and yard “waste” and turn it into a valuable resource to feed my soil. I am copying nature’s closed loop ecology whenever and wherever I try it out.
Josh Steffen, Horticulture and Facilities Manager
*Photo Credit: RAW Sustainable Living